Technical Abstract:
We have shown that the prophylactic administration of Salmonella enteritidis-immune lymphokines (SE-ILK) to day-old chicks provides marked protection from organ colonization by invasive paratyphoid and typhoid salmonellae. In the present study, we evaluated the ability of SE-ILK to: (a) protect chicks from a S. gallinarum (SG) challenge 48 h after SE-ILK treatment and (b) control organ infectivity by horizontally transmitted SG. SE-ILK was injected i.p. into chicks on day-of-hatch. Forty-eight h later, 33% of the chicks (20/60) were challenged by gavage with 10**6 cfu SG. For 10 days after challenge, morbidity and mortality were recorded. Chicks that survived were killed and their livers and spleens cultured for SG. In expt. 1, 80% (16/20) of the seeder control and 38% (15/40) of the contact control birds dies; whereas, no mortality was recorded in the SE-ILK-treated seeder or contact chicks. Similarly, 70% (14/20) of the seeder controls and 35% (14/40) of the contact controls were SG-culture positive. No SE-ILK-treated chicks were SG- culture-positive. In expt. 2, 20% (4/20) of the seeder controls and 23% (9/40) of the contact controls died with no mortality in the SE-ILK- treated birds. Likewise, a marked reduction in organ invasion was found in the SE-ILK-treated seeder (20% vs 70%) and contact chicks (23% vs 50%) when compared to the untreated controls. The results indicate that: (a) SE-ILK protects chicks from SG organ invasion for at least 48 h after injection and (b) SE-ILK may be useful in protecting chicks from organ colonization by horizontally transmitted SG.